The difference between the masking test and the alternate masking test is that the masking test consists of the masking-removal test and the alternate masking test; the masking-removal test is primarily used to differentiate between dominant and occult strabismus, while the alternate masking test is primarily used to differentiate between the presence or absence of occult strabismus, the type of occult strabismus, and the amount of strabismus. To perform the masking-de-covering test, the examiner covers one eye with a masking plate and observes whether the eye rotates after the masked eye is de-covered. If there is rotation, the patient has a dominant strabismus, and if there is movement from outward to inward after de-covering of the covered eye, there is an external strabismus, and from inward to outward, there is an internal strabismus. If there was vertical movement, it indicated vertical strabismus. The alternate cover test starts the examination from covering the strabismic eye, moving the cover plate rapidly from the right eye to the left eye and then back to the right eye, observing the movement of the eye with the cover taken away, and estimating the amount of movement of the observed eye with the degree of the prism with the base facing the direction of the eye’s movement after several alternate coverings. Patients with strabismus are advised to seek prompt hospital consultation to assess their condition and follow the doctor’s instructions for regular treatment.